This section provides background information related to the present disclosure which is not necessarily prior art.
The TFT-LCD (thin film transistor liquid crystal display) is a flat panel display device, and is widely applied in the high performance display field since it has the features of small size, low power consumption, no radiation and low manufacturing costs, etc.
The TFT-LCD consists of an array substrate and a color film substrate. The manufacturing process of the current TFT-LCD mainly comprises four phases, namely, color filter manufacturing, array (array substrate manufacturing) process, cell (crystal liquid cell manufacturing) process and module (module assembling) process. As an important step in TFT-LCD manufacturing, the array process usually comprises forming independent TFT array circuits on a glass substrate, with each array circuit corresponding to one display pixel respectively. Specifically, first a thin film layer may be formed on the glass substrate, then a layer of photoresist is coated on the surface of the thin film layer, and then a patterning process is performed on the above thin film layer through mask exposure, development and etching processes.
Therein, the mask exposure process is to place the substrate formed with the thin film layer and photoresist in an exposure machine, and to place a mask at the side of the substrate facing the light source, and the light source performs localized exposure on the photoresist through the mask. However, during the actual manufacturing process, since the internal cleanness of the exposure machine may be not enough, the mask may be polluted. And since the pattern of the mask is transferred onto the substrate in a 1:1 ratio, defects on the mask will easily cause defects of the thin film pattern after the exposure and transference, so as to affect the reliability of products or lower the excellence rate of products.
In the prior art, usually the internal of the chamber of the exposure machine is cleaned and maintained artificially. Thus, when workers enter into the internal of the chamber of the exposure machine, they also bring some particles into the exposure machine, so that the cleaning effect is reduced. Moreover, the efficiency of artificial cleaning and maintenance is low, reducing the product activation. In addition, the internal of the chamber of the exposure machine may also be cleaned by dust collection equipment. However, since the dust collection principle of the dust collection equipment is implemented by a strong turbulence of airflow, the internal environment factors, e.g., air pressure or temperature, of the exposure machine will be affected. Thus, when the internal temperature of the chamber of the exposure machine changes, the glass substrate will expand and contract, and deform, so the array circuits already formed on the glass substrate will be deformed; and when the internal air pressure of the chamber of the exposure machine changes, the accuracy of the mechanical members performing suction positioning on the glass substrate will be affected, thus patterning defects caused by exposure misalignment will occur.